Various devices are known that detect a vascular pattern in a portion of an individual's retina to identify the individual. Examples of such devices are disclosed in U.S. Pat. Nos. 4,109,237; 4,393,366; and 4,620,318. In these devices, a collimated beam of light is focused on a small spot of the retina and the beam is scanned in a circular pattern to generate an analog signal representing the vascular structure of the eye intersecting the circular path of the scanned beam. In the U.S. Pat. No. 4,393,366, the circular pattern is outside of the optic disk or optic nerve and in the U.S. Pat. No. 4,620,318, the light is scanned in a circle centered on the fovea. These systems use the vascular structure outside of the optic disk because it was thought that only this area of the retina contained sufficient information to distinguish one individual from another. However, these systems have problems in consistently generating a consistent signal pattern for the same individual. For example, the tilt of the eye can change the retinal structure “seen” by these systems such that two distinct points on the retina can appear to be superimposed. As such, the signal representing the vascular structure of an individual will vary depending upon the tilt of the eye. This problem is further exacerbated because these systems analyze data representing only that vascular structure which intersects the circular path of scanned light, if the individual's eye is not in exactly the same alignment with the system each time it is used, the scanned light can intersect different vascular structures, resulting in a substantially different signal pattern for the same individual.